With you colour scheme in mind a few things to add to the suggestions already mentioned. Two common hardy geraniums, Rozanne and Ann folkhard (anne thompson is a refined with less brash leaves) are nice doers. Campanula is a good family to look into.
I'm also a big fan of monarda bee balms and they come in white, pink, purple and red, plus nepeta catmint for their sheer flower power (six hills giant is nice) and for shady spots aquilegia (various colours available), pulmonaria and polemonium.
Posts
Herbaceous salvias, roses, phlox, shasta daisy, honeysuckle
for either:
aster, camassia, campanula, hardy geranium
for shade:
hostas, ferns, primula, anemone (especially the wood anemones)
I'm also a big fan of monarda bee balms and they come in white, pink, purple and red, plus nepeta catmint for their sheer flower power (six hills giant is nice) and for shady spots aquilegia (various colours available), pulmonaria and polemonium.
I live in west central Scotland - not where that photo is...